1. Field of the Invention:
The present invention relates to a novel sodium tripolyphosphate (TPP) having a high speed of hydration, a process for the preparation thereof and its use in detergency applications, for the preparation of compositions or formulations for washing clothes, particularly liquid formulations.
2. Description of the Prior Art:
The typical preparation of detergents is known to this art to begin with an anhydrous TPP, which is converted to hexahydrated TPP in an aqueous detergent medium containing the other constituents of the detergent.
The paste or suspension thus obtained may itself be a liquid detergent, or it may be spray-dried to form a detergent powder.
Considering these methods of preparation, it will be appreciated that the desired TPP must be one which can be hydrated as quickly and as quantitatively as possible. It is also necessary to obtain pastes of low enough viscosity to enable them to be pumped or sprayed under industrial conditions.
It too is known that anhydrous TPP can be obtained in different crystalline forms, phase I or phase II, which behave differently on hydration. Thus, phase I is hydrated very quickly but tends to give rise to solidification and curdling which creates problems in industrial use. Phase II on the other hand gives homogenous pastes, but speed of hydration thereof is unfortunately too slow.
Many processes have been proposed for preparing grades of TPP which specifically have a good hydration speed. In particular, the process described in published European Patent Application No. 101,347 is known. In this process, a TPP is prepared by introducing an orthophosphate solution into a reactor, in which the solution is dispersed in the vortex of a downwardly helically following gaseous phase. The TPP thus obtained has good properties, but it requires specific equipment which is different from that normally used in the TPP industry. Furthermore, there is a demand for a TPP with a still higher speed of hydration and with paste viscosities still lower than those obtained with this product.